Observed Deflections of Reinforced Concrete Slab Systems, and Causes of Large Deflections by ACI Committee 435 D. R. Buettner' Chairman
D. E. Branson R. G. Drysdale' A. Farah A. B. Gogate J. Grossman C-T. T. H s u
S.K. Ghosh' Chairman, Subcommittee on Field Measurements S. V. Kulkarni M. S. Mirza* E. G. Nawy* M. V. Pregnoff G. M. Sabnis' C. G. Salmon
A. Scanlon*
J. M. Spang M. K. Tadros A. F. Shaikh S. Zundelevich
'Members of the Subcommittee on Field Measurements which prepared this report. This report is in two distinct parts. Part I is a summary of published studies on slab deflections (3 from Australia, J from Scotland, 1 from Sweden, 2 from U. S.).The summary focuses on construction practices and materials quality. Comparison of deflections calculated b y various methods with actual long-term deflectionsis made in some cases. Part II summarizes several constructionproblems and material deficiencies which can contribute to large long-term deflections.Focusing on large construction loads, the authors show that construction loads may be considerably higher than design loads and that high construction loads cause high initial deflections because concrete has a lower modulus of elasticity when loaded at an early age. Furthermore, concrete creeps more when it is loaded at an earlyage, thereby causing additional high long-term deflections,even when construction loads are sustained only for a few days. The authors then suggest a method of form removal and reshoring that has proved successful in the New York City area in preventing large slab deflections. Essentially, no more than an 8-footslab span is left unsupported until a slab is mature. A reader interested only in the Committee's findingsand recommendations may proceed straight to Part II of the report. Keywords: concreteconstruction: concrete slabs: creep properties; deflection; flat concrete plates: form removal: loads (forces): modulus of elasticity; reinforced concrete; shoring;shrinkage; two-way slabs.
This document is available as part of Deflections of concrete Structures, SP-86. An abstract of SP-86 was pub-
lished in the ACI J O U R NA L , Proceedings V. 82, No. 4, July-August 1985.
12.5 Reinforced concrete. 12.5.1 General. In the design of reinforced concrete to meet the requirements of the Code, BS 8110, it will usually be most appropriate ...
from the flexural formula M/S, where M is the applied failure bending moment and ..... quadratic equation by using the cracked transformed section method (see ...
ISET Journal of Earthquake Technology, Paper No. 449, Vol. 41, No. .... The lack of information regarding the most relevant mechanical ... occurs within intermediate storeys, more specifically between the 3rd and 7th storeys, attaining its ... reinfo
Abstract. This research is concerned with the mechanical and physical properties of hemp fibre reinforced concrete (HFRC). An experimental program was ...
Download Now for Free PDF Ebook design of reinforced concrete 8th edition solutions manual at our Online Ebook Library. Get design of reinforced concrete ...
The design of reinforced and prestressed concrete has been increasingly ... World War, recommendations for design had been published in the UK in a ...... simplicity. ^This higher value for ym is selected for all calculations of stress for class 2.
In Chapter 7 we showed that the loading actions at any section of a simply-supported beam or cantilever can be resolved into a bending moment and a shearing ...
associated with shear and with bond anchorage. .... increase in yield level or strength of a structure. ...... basis in theoretical and experimental studies as.
the liquefaction of the sand on which the buildings ... frequency characteristics, and duration of large- amplitude .... properties are approximately the same when.
Feb 3, 2010 - requirements of AREA Manual for Railway Engineering,. Chapter .... of the economy of a combination of bridge types. Short ap- ... It is a feasible solution where large overhangs of the deck are ... ed to fit the design conditions. Feasi
section walls especially) or by crushing of the web concrete at the junction of the diagonal struts and the compression flange (in walls with thin webs and/or ...
that the assumptions on which strength calculations are based be clearly ..... sion of fibers is not a problem in sound concrete. They ..... NJIT Model Study : @ - 0% Fiber ..... FRA-ORD-75-93, U.S. Department of Transportation/University of.
The method is not applicable to shear walls or for determining axial forces resulting ...... quadratic equation in k which is solved in terms of the section properties ...
Plate differential equation, based on small deflection elastic theory. 459. Figure 19.1 Deflected ... Equation (19.15) is known as the plate differential equation for circular plates. ..... 2(1 - v') x. Now from elementary two-dimensional stress theo
early reaction and elimination of calcium hydroxide. However, in ...... ene Fibrous Pulp Reinforced Cement Composites, SP-124, American Con- crete Institute ...
... revised 26 June 1981. Fluorescence of Photoreceptor Cells Observed in vivo ... ed fluorescence of the vertebrate retina .... ly by energy transfer from X to M'.
Read and Save Ebook kriechknicken von stahlbetonstutzen creep buckling of reinforced concrete columns flambage des piliers en beton arme sous l action du ...
Aug 6, 2007 - carbon, glass or aramid, new bio-based materials containing natural fibres ... quality interfaces between the inorganic matrix and the fibres.
Three point mild, partial power. Three point mild, partlal power power in approach, power Cut. Just before contact point mild, partial power. f i r s t , bounced ...
Legal kriechknicken von stahlbetonstutzen creep buckling of reinforced concrete columns flambage des piliers en beton arme sous l action du eBook for free ...
